Recent, auxiliary lamps are widely installed to a vehicle body for many objects, such as increasing the traffic safety at night. The current used auxiliary lamps are powered by batteries or by current from the vehicle. If the power is from batteries, since batteries only store finite power so that the batteries must be updated frequently, especially if expensive Hg batteries are used, the power level must be taken care and the update of the batteries is a trouble work.
If power is from the vehicle, the circuit must be redesigned, for example, relay, fuse or wire must be rework. If the rework is not performed well, electromagnetic interference induces, such as the audio, burglar-proof device, computer in the vehicle and alarm panel have noises. All these induce inconvenience in driving a car.